1. Long publication time: If this book has been published for a long time, it may not be sold anymore. Publishers may stop selling some books, either because of copyright issues or because of insufficient market demand.
2. Copyright: If the copyright of this book is transferred to other publishing houses, then Shangshu Culture Media may no longer own the copyright, and it will no longer be able to sell the book.
3. Poor market response: If the book doesn't sell well in the market, the publishing house may reduce the printing volume or stop selling the book.
4. Specific channel sales: If this book is only sold in specific channels, such as only in some bookstores or online, it may not be available elsewhere.
If you want to know more about this book, I suggest you contact Shangshu Culture Media or the author himself.